Apparatus for dressing grinding wheels



July 8, 1952 F. LoHUTKo APPARATUS FOR DRESSING GRINDING WHEELS 3 Sheets-Sheet l Filed Dec. 14, 1948 3. o o. E... o. mw. n M o l lll G |.I 1| m E.. N t enum 3 N .lf2

ATTORNEYS F. LOHUTKO APPARATUS FOR DRESSING GRINDING WHEELS July 8, 1952 5 Sheets-Sheet 2 Filed Dec. 14, 1948 I I J INVENTQR FLonvAN no Hurno' ATTORNEYS July 8, 1952 Filed Dec. 14, 1948 F. LOHUTKO |26 |24 ||6 ze m4 lao loa has se 62 E 1 Y 2 oz l A 'oe o 29 lla fss APPARATUS FOR DRESSING GRINDING WHEELS 3 Sheets-Sheet 3 INVENTOR FLORYAN LOH UTKO UNITED .STATES l --This invention relates `grinding wheels,vand particularly to suchldevices Patented July 8, 1,952

orifice `APPliItAT-US :FOR DRESSING GRINDING WHEELS -Flol-yanLohutko, Detroit, Mich., assigner to The Thompson .Grnder Company,

Springfield,

wOhio, Ya1gcorporation of Ohio ApplicationDecember 14, 1948, Serial No. 65,256

3 'Claims. 1

'to `devices `for dressing especially adapted for-dressing spi-ral grooves, 'such as thread forms onthe periphery of the grinding wheels.

` The grinding `of screw threads, gears,and gear Vlcutters requires the-'grinding wheel to -be'formed to a high degree of accuracy because this-operation on the 'workpiece is generally the last one to which it l issubjected and determines f its knal accuracy. y I' f Y Y 7 PHeretofore, grinding wheels have been gen- Figure Gris a view looking in at -the dressing toolsupport as indicated by vthe arrow-ol on erally dressed by .a diamonddressing'toolfor-this n causeof the fact that the entiregrinding load iscarried'by a small area. y f

Also, the diamond dressing of a grinding whee does vnot produce a particularly sharp 'cutting surface because the diamond shears lthrough both` abrasive and bonding material in thewheel andk leaves it relatively smooth.

.The primary objectof the presentlinvention is to'provide a device for dressing a 'grindingwheel which overcomes Vthe foregoing objections and results in adressed wheel of high accuracy, -which haslonglife .and Vwhich isexceptionally -sharp andfast cutting. Y I

A still further Aobject is to provide-adressing device Vseparate irornaV grinding machine and wherein blank wheels caribe brekenvdownand prepared to the propervform to Vbe ready vto be mounted in a grinding machine. f Y

These and other objects-and Aadvantages will become more apparent uponfreferencetothefol# lowing .description taken in connection with" the accompanying drawings in which:

@Figurel is a plan view of Ya machine constructed according .to` my invention;

:Figure .2 is an end View thereof look-ing inthe direction of the arrow 2 on Figure 1;

Figure 3 is a side elevation vof the machine looking `in-.the .direction of the arrow 3 on Figure 1; L i i Figure e isa schematic view -vci? one form; of hydraulic control circuit for controlling the-hydraulic motor associated lwith the-machine;

Figure 5 is a fragmentary view showing amodifled-constructionlincluding an lautomatic mechanismfor feedingl the wheel -and-dressing-tool:towardeach other;

Figure 4; and

AFigure 1V; y

Figure 7' is a sectionalviewfth-rcugh a control device for regulating the movementof-the wheel; Figure 8 is a diagrammatic electrical control circuit for controlling the several solenoids associated with'the `valves in the hydraulic circuit of -Figure 9 is a fragmentary view showing Aa somewhat modified construction of the inachinelfor employing a different type dressing tool'.

Referring to thedrawings more in detail, the dressing machine according to this inventionfgenerally comprises-a bed YI 0 somewhat L-Sha'p'edand mounting on onefof itslegs a spindle lihousingi. A spindle or shaft Hi extends through the housing I-2 and is journaled therein at one end by the v relatively long sleeve bearings it. At theother end of the housing there isa nutwi-i. and keyed to vthe shaft i4 is a screw 20 threaded to iit the-nut i8. It will be apparent that both the screw and nut are removable from the shaft andhousingin orderftovbe replaced by another nut and'r screw having a diiferent threadrthereon, i-f dired'.

The left end of the shaft I4, as .viewed` in Figure 1, is adapted for receiving fa grinding Wheel supporting block;22 on which is mounted a lgrinding Wheel 24. The mounting ofi-the Wheel on the block and thevblock on the-shaft is substantially conventional and is a duplicate of the means for mounting the dressed' wheel on-the grinding machine in which it willbe used.

At the right end of the shaft I4 the said shaft-is hollow as at 2,6 and extending 'therein is a spindled .shaft 28 which `is drivingly connected with the shaft Mby meansof a splined sleeve The righty end of the `splined shattdsvkeyed to the output shaft 32 Aof `-a reversible hydraulic motor `ill. .It Vwill be--understoodthat the lmotor 34 could be of any type and has vloeenfV illustrated as a reversible hydraulic motori-because of the nicety of control which can be exercisedwcver this type of driving device.

Integral 4With or mounted on the splined shaft 28 is agear''and meshing with this gearis another gear -38 attachedY to a shaft '45@ ,which extends into ya -control box 342. 'The purpose Aof nthe controlbox, as Willbe explained'hereinafteiyis; to control the amount of reciprocation'giventhe shaft M by rotation ofthe Shaft 3,2'.

vOn the other legof the Leshaped bedthereis mounted a cylinder block lli which hasgalnylinder therein that slidably receives .aipistonl. Thepiston'48 is connected with a rod 5D` which is threaded as at 52 to a nut 54. The nut 54 is retained within a crosshead or plate 56 by the antifriction bearings 58 and the clamping rings 60. A knurled knobI as at 62 is connected with the nut and by means of this knob the nut can be turned relatively to the screw and effect axial adjustment of the piston and rod relative to the cros'shead 56. During this adjustment the screw is retained against rotation by the key plate 64 which has a tongue extending into a groove in the threaded portion of the rod 50,

The crosshead 56 is secured to the rearwardly extending arms 66 of a movable platen element 68. The arms 66 are also slidably guided on the cylinder block 44 and thus reciprocation of the piston 48 in the cylinder 46 will also reciprocate the platen element 68.

The platen element mounts a table I8 which is supported on a dove-tail guideway arrangement on the said platen element as indicated at 'i2 in Figure 2. This arrangement is substantially conventional and there are provided means for adjusting the table 'Iii along its dove-tail support in the form of a knurled knob 14, a screwl 'I6 driven thereby, and a nut 7S secured to the platen element. 1

Mounted on the table 'i0 is a plate 80 which is held in positive alignment with the said table by means of the dowel-pin 82. The plate 80 is rotatable about the dowel-pin 82 within predetermined limits and may be clamped in any position of adjustment within those limits by means of the screw and slot arrangement shown at 84 in Figure 6.

In order to effect a very precise angular adjustment of the plate 80 on the table I0 the said plate has one corner notched out as at 86 in order to expose one corner of the table '|0. There is then mounted on this exposed corner of the table 'I0 an accurately iinished dowel 88 and adjacent thereto is an accurately machined arcuate member 90 mounted on the plate 80. By loosening the screws at 84 and inserting precision blocks between the members 88 and 90 in the manner 'of setting a sine bar, the plate 80 can be adjusted very exactly to any degree of angularity relative to the table 10.

The plate 80 mounts a pair of bearing supports 62 which journal, in any conventional manner, a shaft 04. Mounted on the shaft 94 between the bearing supports is a dressing roll 96 having thereon the configuration which it is desired to transfer to the periphery of the grinding wheel 24.

In the arrangement shown the dressing roll 96 has formed thereon a pair of annular grooves which in cross section are the exact counterpart of a thread form or other gear tooth which is to be ground by the wheel 24. Inasmuch as the grooves in the dressing roll are annular and the groove which it is desired to form on the wheel is to extend spirally therearound, it Will be apparent that the mounting of the plate 80 so it can be tilted to an angle relative to the table is an important and essential feature. Furthermore, if the pitch of the groove to be formed on the wheel should change due to a greater size of tooth form or for some other reason, it will be apparent that the position of the plate 80 on the table 'I0 Will have to be further adjusted.

As mentioned before, the drive motor 34 is hydraulic and for supplying power to this motor and also to opposite sides of the piston 48 the hydraulic circuit in Figure 4 may be employed.

In Figure 4 the pump for supply pressure vfluid is indicated at 98 and the suction side thereof is connected with a reservoir |00, while the pressure side thereof is connected with the conduit means |02, one branch of which leads to the inlet of a four-way reversing valve |04 which has its service ports connected as by the conduits |06 and |08 with opposite sides of the piston 48, and which also has exhaust ports connected by the exhaust conduit means I I0 with the reservoir |00.

The motor 34 has its ports connected with the service ports of a four-way reversing valve ||2, the movable part of which is normally centered by the springs I I4 so as to interconnect the two ports of the motor with each other and with the exhaust conduits ||6 and ||8 leading from the valve I I2 to the reservoir |00.

The valve ||2 also comprises a pressure inlet connected by the conduit |20 with the discharge side of the valve |22 which has its inlet connected with the conduit |02.' The valve |22 is a sequencing valve and is normally closed and is adapted for opening upon the establishment for a predetermined pressure on the pilot end |24 rthereof by fluid conducted to the said pilot from the conduit |02 by the pilot conduit |26.

A spring |28 normally urges the movable element of the valve |04 into position to direct fluid to the upper end of the piston 48 thereby to hold the piston and the frame work connected 'therewith in retracted position. Energization of a solenoid S3 connected to the said movable member is effective to shift the said member into, its other operative position wherein the piston 48 and the frame Work associated therewith is shifted in the opposite-direction.

Similarly, the valve |I2 has the solenoids S| and S2 connected therewith and energizationof SI will shift the movable element of the valve l2 into position to drive the motor 34 in a direction to move the shaft I4 leftwardly from its Figure 1 position. On the `other hand, energization of S2 will shift the movable element of the valve I2 into position to drive the shaft I4 rightwardly toward its Figure 1 position.

The solenoids Sl, S2 and S3 are adapted for being 4controlled by the control circuit shown in Figure 8 wherein Athere are the power lines LI and L2. Between these lines there is connected a contactor coil |30 in series with a normally open push button |32. Thepush button |32 Vis by-passed by the normally open blade |34 of the contactor which is in series with the normally closed blade LSIA of a limitswitch LSI. The contactor also has a normally open bladev |316 which is in series with the'solenoid SI and the parallelly connected solenoid S3.

A second contactor |38 is also connected between the power lines L| and L2 and in series with the normally open blade LSIB of the limit switch LSI. The blade LSIB is Vby-passedby the normally open contact |40 of the contactor which is in Series with a normally open 'limit switch LS2. 'I'he contactor also includes a normally open blade |42 which is in series with the solenoid S2. l Y Y 'Ihere is also provideda normally closed limit switch LS3 in series with the contactor |30 which is adapted for being opened by engagement with the wheel supporting member 22 for halting operation of the motor 34 in `event the said wheel should be driven beyond its normal limits' of travel. l Y Y 1 The limit switches LSI and ,LS2 .aremounted Within the control unit 42 as vshown inFigure 7. In this figure it will be noted that the shaft40is threadedv .internallyaofthe unitfand-fmounts a :cam block 1144 whichfisad'apted rin .its left Shand 'position for.Y engaging andv opening the. limit switch LS-2 andinit's `right .handfor engaging the limit switch LS| thereby to open the blade LSIA 'thereof :and to closeithe blade LS IB thereof. Y

Should it be Jdesirecl to provide1for an automatic irl-feed 'fof they dressing Aroll.towarcl"the' vwheelaxis, thenut 54 may vhave connected therewith a four-way reversing valve |50 which is` urged into cnef-operativeposition by a spring |56 I f and into another byk energization ofal solenoid-S4.

The solenoid S4 is connected as shown in Figure 8 in parallel with the solenoidsS-I Vand S3 and through a selector switch I |50 which 'can be closed to make the automatic in-feed mechanism operative and openedftoV make the-said mechanism inoperative. Y f

`Operdtion In operation, a wheel to be dressed is mounted on the wheelsupporting block 22 andsecured `thereto infthe usual manner. At that time the shaft I4 occupies its Figure 1` position andthe dressing ,roll 9,6. will also occupy Aits Figure 1 vposition, wherein it is retracted from the periphery of the'wheel 24.., t

A dressing cycle isy commenced by closing the switch r|32 which energizes the contactor |30 i and therethroughv energizes the solenoids SI `and S3. lilnergization of Sl will shift the movable elementlof the valve Il2int'oposition to supply .pressurev iiuid to thelmotor 34 to drive itin a direction to advance the shaft I4 leftwardly. At the same time the solenoid S3 shifts the movable element of the valver |04 into position to direct pressure fluid to the lower side of the piston 48' thereby to move the said piston and the structure associated therewith toward the wheel axis. This positions a dressing rollin proper relationship to the periphery of the grinding wheel.

It will be noted that at this time the piston and the frame work connected therewith will be completely shifted before the motor 34 comfto'its startingpo'sition When the wheell has Areached its starting `position the cam y|44 will engage the limit switch L52` and open the same and thereby de-energize -the fcontactor |38, and, thereby de-energize the -soleno'idvSL lIf the selector switch |60 is closed at the time the Ypush button |32 is closed then lan-automatic ,1in-feed' of the=-dressing roll takes place of 'a predetermined amount. -If the selector switch |60 .is fnot closed then the dressing r'oll can be fed incbynmanual operation of the .knurl'ed hand 'Wheel-'62.- Y l Y 2: The yembodiment vdescribed above utilizes a lcrushing roll type dressing tool-land it will '-be apparent that such #a dressing roll can be mounted forvfreeA rotation and that it will autofmaticallyproperly lalign with the wheel being dressed; Should it be desiredto employ a -cutting or picking type tool, thenithe said-tool may be driven in synchronismv'with the grinding wheel. Anlarrangement of this'typeisi-llustrated in `lligureri) wherein the `dressing roll 96 is replaced by a cutting orpicking type dressing roll k|66 and the supporting shaft A|68 thereof .is-'connected through the universal joints |10 and'shaft |12 with the geared take-off |14 leading from the drivenfge'ar 36.

f- By this arrangement the :wheel and dressing tool are `always Vpositivelysynchronized and thus each time-the wheel vreciprocates'into engagement with the 'dressingtoolit willengagetherewith in the proper fmanner.- 1

The dressing tool shown in -Figurel 9 is, of course, tiltable as is the dressing rollshown in Figure 1, and is advanced toward thewheel yaxis and retracted therefrom in synchronism with the reciprocationy of the said wheel.

mences to operate due to the sequencing valve |22 which requires that a predetermined pressure be built up in the conduit greater than that required to shift the piston 48 and the mechanism driven thereby before the said valve will open to admit pressure fluid to the motor 34.

Also, during operation of the motor 34 for driving the shaft I4 leftwardly, the throttle valve |62 may be adjusted for controlling the speed of operation of the said motor thereby to maintain the peripheral speed of the grinding wheel within the proper limits.

As the motor 34 drives the shaft I4 into rotation and reciprocation, the threaded shaft 40 is also driven and carries the block |44 toward the limit switch LSI. When the block reaches the said switch, and the position of the switch has been predetermined by adjusting its position by the rod |64, the said switch is actuated to open the blade LSIA, thereby to deenergize the contactor |30, and therethrough to deenergize the solenoids SI and S3 and to close the blade LSIB thereof, thereby to energize the contactor |38, and therethrough to energize the solenoid S2. At this time the piston 48 and the mechanism driven thereby retract from the wheel axis and the motor 34 is reversed to retract the wheel yIt will be understood' that this invention is susceptible to modification in order to adapt it to different usages and conditions and, accordingly, it is desiredto comprehend such modifications within this invention as may fall within the scope of the appended claims.

I claim: v

1. In combination in a device for dressing a grinding wheel; a bed, a spindle housing on said bed, a shaft extending through said housing and having a bearing support at one end thereof and a screw threaded support at the other end thereof; mounting means for a wheel to be dressed on the said one end of said shaft, a fluid roperable motor splined to the other end of said shaft whereby energization of said motor will bring about rotary and axial movement of said shaft and of a wheel mounted thereon, an annularly ribbed crush dressing roller tiltably mounted on said bed, fluid operable piston means operably connected with said roller for moving said roller in one direction to place it in operative alignment with the periphery of a wheel carried by said shaft and to retract it from operative alignment with said wheel, interconnected reversing valve control means having conduits connecting the said valve control means with said fluid motor and said piston means, said yvalve control means being operable for energizing said motor for one direction of rotation and said fluid operable means to move said roller into operative position and also operable to reverse said motor and to operate said fluid operable means to retract said roller from said operative position, and means responsive to a predetermined travel of said motor while said roller is in retracted position for automatically de-energizing said motor.

A 2.1'In a deviceiordressing a-grindingwheel; a

bed, a spindle housing on saidybed, a shaft in said Vmotoiand said piston, said valves being operable to control the energization ,of' said motor and direction;v of 4fluidfjow `in said piston, means to advance and retract-said rolL;l

3. In combination, inga device for dressing a grinding wheel; a bed, a spindle housing'on said bed, a shaft extending throughsaid housing and having a bearing support at one end thereof and a screw threaded'support at the other endthereof, mounting means for awheel to be dressed on the said one end of said shaft, a iluidoperable motor splined to the other end of said shaftwhereby energization vof said motor will bring about rotary and axial movement of said shaft and of a wheel mounted thereon,- an annular ribbed crush dressing roller tiltably mounted on said bed for intimate pressured engagement with said wheel, iiuid operable-piston means operably connected with saidvroller formoving said roller in one direction to place it in operativealignment with the periphery of said Wheel carried by saidshaft and to Aretract it from operativeralignment with said wheel, interconnected reversing valve controll means having conduits connecting the said valve means with vsaid fluid motor and said piston means, said valve means being operable for energizing said motor for one direction of rotation and said fluid operable means to move said roller into operative position, and an electric circuit arrangement including solenoids operably connected with Said valve means operable to reverse said motor and to operate said uid operable means to retract said roller from said operative position.

FLORYAN LOHUTKO.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,501,230 Olson July 15, 1924 1,594,407 Durkee Aug. 3, 1926 1,842,538 Burgess Jan. 26, 1932 1,899,654 Ward Feb. 28, 1933 2,131,939 Drake Oct. 4, 1938 2,178,875 Kearns Nov. 7, 1939 2,188,947 Horstmann Feb. 6, 1940 2,227,715 Horstmann Jan. 7, 1941 2,264,257 Garside Nov. 25, 1941 2,286,046V Wichmanl June 9, 1942 2,300,363 Snader Oct.`2'7, 1942 2,363,559 Selnes Nov. 28, 1944 2,482,784 Lohutko- Sept. 27, 1949 l FOREIGN PATENTS VNumber Country Date 573,943 Germany Apr. 7, 1933 

